I'd like to throw a recommendation out there for Dying Light. Very fun take on the zombies, open world, and survival. It is basically a functioning version of Dead Island (same devs) with a lot of the dumb stuff fixed. The hook is that you have to rely more on melee weapons. Using guns is allowed, but zombies are cued in on sound in particular. So if you fire your gun, expect to have zombies coming in from all over.